(a) Field of the Invention
The present invention relates to an assembling machine for Ni-MH batteries and an assembly process thereof, more particularly, to an automated assembling machine for a positive electrode plate Ni-MH battery which is a secondary battery and the assembly process using the assembling machine thereof.
(b) Description of the Related Art
With the rapid increase in the spread of portable devices such as personal communication systems and notebook computers, there has been a demand for the development of secondary batteries that are compact, lightweight, and have high energy density. The introduction of environmentally friendly zero-emission electric vehicles has also resulted in the further demand for the development of secondary batteries as power sources.
Batteries generally convert chemical energy into electrical energy by the electric potential difference between metals, and can be classified as primary (nonrechargeable) batteries, secondary (rechargeable) batteries, and special batteries such as solar cells. Primary batteries can be further classified as manganic cell, alkaline cell, mercuric oxide cell, and silver oxide cell batteries depending on the type of electrode, while secondary batteries can be classified as Ni-MH batteries using metal-hydroxide as the electrode, sealed nickel-cadnium batteries, lithium-metal batteries, lithium-ion batteries, and lithium-polymer batteries.
While primary batteries have disadvantages such as short life, low capacity, and nonrechargeability, secondary batteries have excellent performance characteristics for electric vehicles due to their high capacity and long life. Ni type batteries are widely used as secondary batteries because they have proven to have good recycling characteristics and environmental performance.
However, the above Ni type batteries, especially Ni-MH batteries have the disadvantage of low production efficiency that results from a large number of operational steps and a long lead time due to manual assembly operations.
FIG. 1 shows the production process for the positive electrode plate for Ni-MH batteries with previously employed manual assembly operations consisting of ten operational steps.
As indicated in FIG. 1, a line operator cuts a positive electrode plate 201 of a predetermined length from a Ni foam coating roll using a cut-off machine, and marks an edge of a tab 205 area with a press to facilitate the attachment of a tab 203 of a predetermined length. After cutting tabs 205 from a Ni foil roll, two of these tabs 203 are. folded and temporarily welded at their. corner. The Ni foam coated positive electrode plate 201 is inserted in the fold of the tabs, and they are then temporarily welded together. At this point, the welding of the tab to the positive electrode plate 201 is completed using a welding machine with a wider tip. The welded positive electrode plate 201 is then coated with nickel hydroxide paste by manual operations, and after the paste has dried, the positive electrode plate is cut using a cut-off machine. The positive electrode plate is then blanked using a press, and any residual nickel hydroxide from the coating process that may exist between the tabs can be cleaned using alcohol, and the final product is complete.
However, as the above assembly process for a positive electrode plate for Ni-MH batteries by previously employed manual assembly operations is dependent on manual operations using manual tools, the total manufacturing expense and product reject rate is high due to a large number of assembly operational steps.
The present invention made to solve the above problems provides the assembling machine for a positive electrode plate and an assembly process thereof, wherein the positive electrode plate for Ni-MH batteries can be made through an automated on-line production process so that cost, time, and reject rate of production can be substantially reduced, and hence production efficiency can be maximized.
The above described assembling machine for the positive electrode plate consists of an electrode plate feeding unit having a magazine that loads and stacks the cut positive electrode plate manually, an active material removing unit having an ultrasonic cleaner that removes an active material from an active material removal area of the positive electrode plate, a tab feeding unit transferring a tab strip from a tab strip roll, a tack welding unit that temporarily welds an edge of a tab strip that is transferred from the tab feeding unit to upper and lower faces of the active material removal area of the positive electrode plate, a cutting unit that cuts rectangular tabs of a predetermined size from the temporarily welded tab strip, a finish welding unit that fully welds the temporarily welded tab, a calendar rolling unit that presses the finish welded positive electrode plate to a predetermined thickness, and a blanking press unit that cuts the calendar rolled positive electrode plate into a desired shape.